NUMERICAL INVESTIGATION OF THE STRUCTURAL BEHAVIOR OF REINFORCED CONCRETE BEAMS WITH CRUSHED CONCRETE AGGREGATE

Recycling of waste materials produced from the construction and demolition activities is becoming a demand for modern societies willing to achieve environmental sustainability. To date, the use of crushed concrete aggregate (CCA) in replacement of natural coarse aggregate to produce high quality concrete is very limited. This can be attributed to the missing information on the properties of the original concrete before crushing, the limited data that clarifies the influence of using CCA on the material properties of the concrete mixture as well as the overall structural behavior of the reinforced concrete element in which it is used. An experimental testing program has been conducted on reinforced concrete beams to assess the influence of CCA replacement ratio on their structural performance and the results have been briefly discussed in this paper. The primary aim of the study presented herein is to numerically evaluate the influence of the concrete compressive strength (fcu) and the shear span to depth ratio (a/d) on the structural performance of reinforced concrete beams casted with two different concrete mixtures incorporating 0% and 100% CCA. Accordingly, ten beams have been modelled using ANSYS finite element software with two control beams being validated with the experimental data. The results demonstrate the increase of the load carrying capacity and ductility of beams with 100% CCA with increasing the fcu. On the contrary, increasing the shear span to depth ratio leads to the reduction in the capacity of the beams casted with the two different concrete materials. As a final conclusion, the results of the performed numerical analysis designate undesirable structural performance of the concrete beams with 100% CCA. Therefore, it is not recommended to use concrete mixtures with full replacement of natural coarse aggregate by CCA in casting concrete structural members where ductile behavior is indispensable.